Many computer-based teaching machine designs store questions or problems to present to the user as prompts for the correct answer or solution. The user's responses are evaluated by comparison to the stored answer and in the more sophisticated machines, the process control is influenced by the evaluation. However, existing art has a number of weaknesses. Existing art requires the user to respond with complete answers. Existing art informs the user that an incorrect answer was incorrect without informing the user exactly what was incorrect about his answer; the user often cannot identify exactly what was incorrect about his answer. Existing art normally responds to correct answers by immediately presenting the next answer. The previous correct answer disappears. Thus the user could have guessed the correct answer without actually knowing what it was, or immediately forgotten what the correct answer was. In addition, existing art processes answers as either correct or incorrect.
U.S. Pat. No. 5,540,589 to Waters, titled Fault-tolerant Audio Interactive Tutor, attempts to address some of the problems of existing art by considering answers to be correct if they are close enough, and U.S. Pat. No. 5,577,919 to Collins, et al., attempts to solve problems of the existing art by seeking to determine not whether the answer is correct or not, but merely whether the user thinks the answer is correct. Neither of these approaches attempts to deal with partially correct answers.
Other problems of existing art include the fact that existing art does not make use of subliminal suggestion to prompt the user with the correct answer. Further, existing art does not present the user with prior errors. In addition, importantly, existing art does not attempt to deal with the problem of graded interval recall taking actual elapsed real time into consideration. Material is reviewed on the basis of correctly/incorrectly answered priority, the most crude form of which is to simply repeat incorrectly answered questions. Attempts to prioritize the sequence of material on a more intelligent basis (see, U.S. Pat. No. 4,193,210 to Turnquist) can result in delays of reviews until long after the material has been lost from short-term memory.